High altitude balloon and method of making the same



June 26, 1962 H. E. FROEHLICH 3,

HIGH ALTITUDE BALLOON AND METHOD OF MAKING THE SAME Filed June 50, 1959mmvroa HAROLD E. FROEHLICH 04; m A-r-rys United States Patent M3,041,013 HIGH ALTITUDE BALLOON AND METHOD OF MAKING THE SAME Harold E.Froehlich, Oak Grove, Minn., assignor, by

mesne assignments, to the United States of America as represented by theSecretary of the Navy Filed June 30, 1959, Ser. No. 824,165 1 Claim.(Cl. 244-31) This invention relates to high altitude plastic filmballoons and is concerned more particularly with those of the type madeof a number of tailored gores.

In the manufacture of such a balloon, it is the practice to provide anelongated table one longitudinal edge of which is straight and the otherconvexly curved to the shape each longitudinal edge of each gore is tohave, the part of maximum width being half the maximum width of the goreto be formed; provide a roll of the plastic film material with thematerial in the form of lay flat tubing whose circumference is usuallythe maximum width of the gores to be formed; draw the material off theroll and onto the table so that one fold extends along the straight edgeof the table; cut the material to gore length from the roll; and, usingthe curved edge of the table as a template, cut the two plies of thematerial to the shape of the template. The result is a gore symmetricalabout its longitudinal axis and converging in width toward its ends. Theshape of the curve is related to the number of gores that are to be usedso that, when the gores are longitudinally heat-sealed in acircumferential series, the balloon will have a natural shape uponinflation with lift gas. A natural shape balloon is one in which filmstresses are primarily longitudinal. It is flatter on top than a sphereand fuller on the bottom than a cone. With a given table, only one sizeof natural shape balloon having a predetermined number of identicaltailored gores of predetermined shape can be made. In such a balloon,therefore, each gore subtends an aliquot part of 360.

In a plant for manufacturing this type of high altitude balloon thereare tables in a suflicient number of sizes to manufacture those sizes ofballoons for which there is frequent demand. There is occasionally aneed for an off-size balloon, to carry a given load to a predeterminedaltitude. It would of course be most uneconomical to provide tables inall of the sizes needed to make all possible sizes of balloon that mightpossibly be needed, however rarely, or even to produce a special tablewhenever an off-size balloon is needed.

If all of the gores of a balloon are formed as above, the balloon willhave an efficient structural shape. However, a balloon which has anexcess amount of circumferential material will still take its naturalshape and perform very satisfactorily. The provision of an oilsizeballoon which is nearly tailored to the natural shape, without requiringa special table in its manufacture, is the salient object of theinvention.

Further objects and advantages of the invention will appear as thedescription proceeds.

The invention will be better understood on reference to the followingdescription and the accompanying drawing, wherein:

FIG. 1 shows an elevational view of a fully inflated balloon constructedin accordance with the invention.

FIG. 2 is a top plan view of the same.

FIG. 3 is an exploded view on a reduced scale showing in development twodiflerent shaped gores appearing next to each other in the finishedballoon.

Referring now more particularly to the drawing, disclosing anillustrative embodiment of the invention, there is shown at a fullyinflated multi-gored balloon em- 3,041,013 Patented June 26, 1962bodying features of the invention. The balloon 10 is formed of identicalsections or groups 12 of identical tailored gores 14, and individualrectangular gores 16 of the same length as the gores '14, the groupsalternating with the gores 16. Each gore 14 is symmetrical with re spectto its longitudinal axis and of progressively reduced width from anintermediate portion 18 to its ends 20 and 22, the shape and number ofgores 14 being such that, if the gores 16 were replaced by gores 14, theensemble would form a structurally eflicient natural shape balloon. Thegores .16 being rectangular, however, the balloon 10, instead of beingof perfect natural shape without folds, will assume its natural shapeupon inflation, the rectangular gores being gathered in generallylongitudinal folds as indicated at 24 and 26 so that each rectangulargore has the same projected shape as a gore 14, the rectangular goresthus providing increasing circumferential fullness from the equatorialplane of the balloon, i.e., from the plane of maximum diameter of theballoon, toward the top of the crown and toward the apex of the conicalportion. The top of the balloon may be gathered in the form of a tubewhich is extended through and clamped in any suitable fashion againstthe collar 28 of an end fitting.

The fullness provided by the excess material at 24 and 26 renders thematerial and seams substantially free of circumferential stress, so thatsubstantially all of the stress is oriented longitudinally, in whichdirection the material is normally strongest. The shape of the balloonwill be altered very slightly due to the excess material.

If desired, an elf-size balloon in accordance with the invention couldbe made in which the gores 16 are replaced by ofl-shaped gores each ofwhich converges like a gore 14 toward either end and is rectangulartoward its other end. If such replacement gores are made with the upperportions rectangular, the resulting balloon at the top will appear asindicated in FIG. 2. Each such replacement gore can be laid out on thesame table used in shaping the gores 14, and cut like the gores 14 butonly to the extent to impart the desired rectangular-convergent shape.The resulting balloon will thus have less excess material than theballoon having fully rectangular replacement gores and therefore willweigh slightly less.

One or more off-shaped (rectangular or rectangularconvergent) gores maybe employed in any balloon, so that a number of olf-size balloons ofdifferent volumes can be made with the same table.

While preferred embodiments have been described in some detail, theyshould be regarded as examples of the invention and not as restrictionsor limitations thereof as changes may be made in the materials,construction and arrangement of the parts without departing from thespirit and scope of the invention.

1 claim:

In a method of making a substantially natural shape balloon for carryinga load whose weight is greater than the weight to be carried by anatural shape fully tailored multi-gore stock size balloon having apredetermined number of gores and less than the weight to be carried bythe next larger stock size natural shape fully tailored multi-goreballoon, the steps of forming a majority of said predetermined number ofelongated tailored gores of which the smaller stock size balloon wouldbe made, forming identical rectangular gores of the same length as thetailored gores and each of a width equal to the maximum width of each ofthe tailored gores, the total number of said majority of tailored goresand said rectangular gores being equal to said predetermined number,heatsealing the longitudinal margins of said rectangular gores and saidmajority of tailored gores in a circumferential series to therebyprovide an envelope having the same with the same supply roll of filmand the same tailored 10 2,880,946

gore pattern used in the making of the smaller stock size balloon andwill have a substantially natural shape when carrying a predeterminedoff-weight load greater than that which the smaller stock size fullytailored 5 natural shape balloon is designed to carry.

References Qited in the file of this patent UNITED STATES PATENTSStinger et a1 Mar. 8, 1955 Froehlich Apr. 7, 1959

